Semiconductor device and method for manufacturing the same

ABSTRACT

A method includes: mounting a plurality of semiconductor elements on a substrate having wirings; connecting electrically electrodes of the semiconductor elements and the wirings; sealing the semiconductor elements with a resin, which is carried out by bringing a thermal conductor having a concavity and the substrate to be in contact with each other so that the semiconductor elements are positioned within the concavity and by filling the concavity with the resin; and separating respective semiconductor elements  1 . In the resin-sealing step, in a state where the thermal conductor is arranged with its concavity facing up and the concavity of the thermal conductor is filled with a liquid resin, the semiconductor elements are clipped in the liquid resin in the concavity and the liquid resin is solidified. Due to these steps, a semiconductor device can be manufactured without experiencing troubles such as short circuit of the metal thin wires or imperfect filling of resin during the manufacturing steps, and thus semiconductor devices with stable quality can be manufactured.

This application is a division of application Ser. No. U.S. 10/558,663,filed Nov. 29, 2005, which is a U.S. National Stage application ofInternational Application No. PCT/2004/017179, filed Nov. 18, 2004,which application is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device suitably usedfor a case in which semiconductor elements that generate much heat powerare mounted, and a method for manufacturing the semiconductor device.

2. Description of Related Art

With the recent trend toward multifunction and reduction in size andthickness of electronic equipment, the semiconductor devices have becomesmaller and thinner, and the number of terminals tends to increase. Forcoping with this tendency, a so-called BGA (Ball Grid Array) package hasbeen used. Unlike a conventional QFP (Quad Flat Package), a BGA packagedoes not have an external lead protruding in the lateral direction.Instead, the BGA package has solder balls that are arranged in a matrixon the lower surface of a substrate and that serve as externalelectrodes for an electric connection with a mother board.

Since it is expected that semiconductor elements generating much heatare mounted on such a BGA package, heat diffusion is taken intoconsideration in the designing (see JP H08-139223 A for example).

FIG. 17 is a cross-sectional view showing a configuration of aconventional semiconductor device 101. FIG. 18 is a perspective viewshowing a thermal conductor 119 of the semiconductor device 101 in FIG.17. Wiring patterns 112 are formed on the both surfaces of a substrate113 made of an insulating resin, and the wiring patterns 112 areconnected electrically to each other through viaholes 117. Asemiconductor element 111 is mounted on one principal surface of thesubstrate 113 through an adhesive 114 and connected electrically to thewiring pattern 112 on the substrate 113 through metal thin wires 115.

The thermal conductor 119 is made of a material having a preferablethermal conductivity such as Cu, Cu alloy, Al, Al alloy and Fe—Ni alloy,and it covers the surface of the substrate 113 on which thesemiconductor element is mounted (semiconductor-element-mountingsurface). The thermal conductor 119 has a contact portion 122 that is incontact with the substrate 113, an inclined portion 121 formed with aninclination from the contact portion 122, and a flat portion 120 formedcontinuously from the inclined portion 121 and to be parallel to thesubstrate 113. As shown in FIG. 18, a plurality of openings 131 areformed on the contact portion 122 and on the inclined portion 121. InFIG. 17, a sealing resin 116 is filled in the spacing between thethermal conductor 119 and the substrate 113 so as to seal thesemiconductor-element-mounting surface of the substrate 113, thesemiconductor element 111, the adhesive 114, and the metal thin wires115 integrally. Ball electrodes 118 are arranged in a matrix on one ofthe wiring patterns 112 of the substrate 113 opposite to thesemiconductor-element-mounting surface.

The semiconductor device 101 is configured so that heat generated by thesemiconductor element 111 is diffused through the viaholes 117 and theball electrodes 118, and furthermore, the heat is diffused also from thesemiconductor-element-mounting surface of the substrate 113 through thethermal conductor 119, and thus the semiconductor device 101 hasexcellent heat diffusion.

Furthermore, by providing a heat sink or the like (not shown) on anupper surface of the thermal conductor 119, namely, a part at which thesealing resin 116 is not formed, the effect of heat diffusion from thesemiconductor-element-mounting surface can be enhanced further.

Next, a method for manufacturing the conventional semiconductor device101 will be described below. FIGS. 19A-19F are cross-sectional viewsshowing a process of manufacturing the semiconductor device 101. First,as shown in FIG. 19A, a substrate 113 with wiring patterns 112 formed onboth surfaces thereof is prepared, and the adhesive 114 is applied onpredetermined positions of the semiconductor-element-mounting surface ofthe substrate 113. Next, as shown in FIG. 19B, the semiconductor element111 is placed on the adhesive 114 and adhered securely. Next, as shownin FIG. 19C, an electrode (not shown) of the semiconductor element 111mounted on the substrate 113 and the wiring pattern 112 formed on theupper surface of the substrate 113 are connected electrically to eachother through the metal thin wires 115. Next, as shown in FIG. 19D, thethermal conductor 119 is brought into contact with the substrate 113 soas to cover the semiconductor element 111.

Next, as shown in FIG. 19E, the substrate 113 in contact with thethermal conductor 119 is set on a lower mold 133 of a sealing mold 134,and sealed securely with an upper mold 132 of the sealing mold 134. Atthis time, the lower surface of the upper mold 132 of the sealing mold134 and the upper surface of the thermal conductor 119 are in contactwith each other. In this state, a sealing resin 116 is injected in aninjection direction 136 from an injection gate 135 formed horizontallyin the upper mold 132 of the sealing mold 134. As a result, through theopenings 131 of the thermal conductor 119 as shown in FIG. 18, thesealing resin 116 enters the space between the thermal conductor 119 andthe substrate 113. At that time, in the vicinity of the injection gate135, the sealing resin 116 is on the upper surface of the thermalconductor 119. After curing the sealing resin 116, the upper mold 132and the lower mold 133 of the sealing mold 134 are disengaged. Finally,as shown in FIG. 19F, the ball electrodes 118 are formed by attachingsolder balls to external pad electrodes of the wiring pattern 112 formedon a surface of the substrate 113 opposite to thesemiconductor-element-mounting surface, thereby configuring externalterminals. In this manner, the semiconductor device 101 can bemanufactured.

The conventional semiconductor device 101 can diffuse heat since theupper surface of the thermal conductor 119 is exposed from the sealingresin 116. However, since in the resin-sealing step, the resin isinjected from the injection gate 135 provided at the sealing mold 134(hereinafter, this method is referred to as a side gate method), themetal thin wires 115 will be deformed easily due to the resin injection.

Here, the deformation of the metal thin wires during the resin-sealingstep in the side gate method will be described in detail with referenceto FIGS. 20A-20C. FIGS. 20A-20C show a typical BGA, from which a thermalconductor is omitted for clearly showing the phenomenon.

FIG. 20A is a cross-sectional view showing a state just before aresin-sealing in the side gate method, and that corresponds to thecross-section taken along the line J-J′ in FIG. 20B and FIG. 20C. FIG.20B is a top view showing the appearance of the metal thin wires 115before resin injection, and FIG. 20C is a top view showing theappearance of the metal thin wires 115 and a flowing pattern of theresin after the resin injection.

As shown in FIG. 20C, the resin injected from the injection gate 135 ina direction 136 moves forwards while forming ripples centering on theinjection gate 135. Here, each of dotted lines 137 indicates a positionthe resin reaches at a point of time.

The deformation level of the metal thin wires 115 has a relationship to“resin viscosity”, “resin current speed”, “angle of the tip of theflowing resin with respect to the metal thin wires” and the like. Asshown in FIG. 20B, the metal thin wires 115 are arranged radially fromthe center of the semiconductor element 111. Therefore, as shown in FIG.20C, after the resin injection is finished, some of the metal thin wiresthat are located in the vicinity of the injection gate 135 or at theside diagonally opposite to the injection gate 135 and thus not angledsubstantially with respect to the flowing direction of the resin are notdeformed substantially. However, the remaining metal thin wires 115 aredeformed depending on “resin current speed”, “angle of the tip of theflowing resin with respect to the metal thin wires”, and the like.

As a result, in a case of resin-sealing of the conventional side gatemethod carried out for a semiconductor device with metal thin wires 115arranged across at a high density in accordance with the demand forsmaller device and increase in the number of terminals, problems such asa short circuit may be caused by deformation of the metal thin wires 115when the adjacent metal thin wires 115 are arranged at a narrow pitch.

Moreover, when the thermal conductor 119 as shown in FIG. 18 isincluded, the flow of the sealing resin is complicated and the fluiditydeteriorates. This may cause a problem of imperfect filling of thesealing resin as well as the problem of deformation of the metal thinwires.

SUMMARY OF THE INVENTION

Therefore, with the foregoing in mind, it is an object of the presentinvention to provide a semiconductor device with stable quality, whichcan be manufactured without problems such as a short circuit in themetal thin wires or imperfect resin filling during a manufacturingprocess. Another object of the present invention is to provide a methodfor manufacturing the semiconductor device.

A first method of the present invention for manufacturing asemiconductor device includes: mounting a plurality of semiconductorelements on a substrate having wirings; connecting electrodes of thesemiconductor elements and the wirings electrically; sealing thesemiconductor elements with a resin, which is carried out by bringing athermal conductor having a concavity and the substrate to be in contactwith each other so that the semiconductor elements are positioned withinthe concavity and by filling the concavity with the resin; andseparating the respective semiconductor elements. For solving theabove-described problems, the method is characterized in that, in theresin-sealing step, in a state where the thermal conductor is arrangedwith its concavity facing up and the concavity of the thermal conductoris filled with a liquid resin, the semiconductor elements are dipped inthe liquid resin in the concavity and subsequently the liquid resin issolidified.

A second method of the present invention for manufacturing asemiconductor device includes: mounting a plurality of semiconductorelements on a lead frame; connecting electrodes of the semiconductorelements and the lead frame electrically; sealing the semiconductorelements with a resin, which is carried out by bringing a thermalconductor having a concavity and the lead frame to be in contact witheach other so that the semiconductor elements are positioned within theconcavity and by filling the concavity with the resin; and separatingthe respective semiconductor elements. For solving the above-describedproblem, the method is characterized in that, in the resin-sealing step,in a state where the thermal conductor is arranged with its concavityfacing up and the concavity of the thermal conductor is filled with theresin, the semiconductor elements are dipped in the liquid resin in theconcavity and the liquid resin is solidified.

A first semiconductor device of the present invention includes asemiconductor element, a substrate on which the semiconductor element ismounted, a thermal conductor, and a sealing resin that is provided intothe spacing between the substrate and the thermal conductor so as toseal the semiconductor element. For solving the above-described problem,the thermal conductor is bonded to the surface of the sealing resin soas to cover the sealing resin.

A second semiconductor device of the present invention includes asemiconductor element, a lead frame on which the semiconductor elementis mounted, a thermal conductor, and a sealing resin that is providedinto the spacing between the lead frame and the thermal conductor so asto seal the semiconductor element. For solving the above-describedproblem, the thermal conductor is bonded to the surface of the sealingresin so as to cover the sealing resin.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a top view showing a configuration of a semiconductor deviceaccording to Embodiment 1 of the present invention.

FIG. 1B is a cross-sectional view taken along the line A-A′ in FIG. 1A.

FIGS. 2A-2F are cross-sectional views showing a process of manufacturingthe semiconductor device.

FIG. 3 is a plan view showing a thermal conductor group for thesemiconductor device.

FIG. 4 is a plan view showing a thermal conductor group for thesemiconductor device.

FIG. 5 is a plan view showing a thermal conductor group for thesemiconductor device.

FIG. 6A is a top view showing a variation of the semiconductor device.

FIG. 6B is a cross-sectional view taken along the line B-B′ in FIG. 6A.

FIG. 7A is a top view showing a configuration of a semiconductor deviceaccording to Embodiment 2 of the present invention.

FIG. 7B is a cross-sectional view taken along the line C-C′ in FIG. 7A.

FIG. 7C is a cross-sectional view taken along the line D-D′ in FIG. 7A.

FIGS. 8A-8F are cross-sectional views showing a process of manufacturingthe semiconductor device.

FIG. 9A is a top view showing a variation of the semiconductor device.

FIG. 9B is a cross-sectional view taken along the line E-E′ in FIG. 9A.

FIG. 10A is a top view showing a configuration of a semiconductor deviceaccording to Embodiment 3 of the present invention.

FIG. 10B is a cross-sectional view taken along the line F-F′ in FIG.10A.

FIGS. 11A-11F are cross-sectional views showing a process ofmanufacturing the semiconductor device.

FIG. 12A is a top view showing a configuration of a semiconductor deviceaccording to Embodiment 4 of the present invention.

FIG. 12B is a cross-sectional view taken along the line G-G′ in FIG.12A.

FIGS. 13A-13F are cross-sectional views showing a process ofmanufacturing the semiconductor device.

FIG. 14A is a top view showing a variation of the semiconductor device.

FIG. 14B is a cross-sectional view taken along the line H-H′ in FIG.14A.

FIG. 15A is a top view showing a second variation of the semiconductordevice.

FIG. 15B is a cross-sectional view taken along the line I-I′ in FIG.15A.

FIG. 16 is a cross-sectional view showing a process of manufacturing thesecond variation of the semiconductor device.

FIG. 17 is a cross-sectional view showing a configuration of aconventional semiconductor device.

FIG. 18 is a perspective view showing a thermal conductor of thesemiconductor device.

FIGS. 19A-19F are cross-sectional views showing a process ofmanufacturing the semiconductor device.

FIG. 20A is a cross-sectional view showing a state before resininjection, in a process of manufacturing a conventional semiconductordevice.

FIG. 20B is a top view showing a state before resin injection, in aprocess of manufacturing the semiconductor device.

FIG. 20C is a top view showing a state after resin injection, in aprocess of manufacturing the semiconductor device.

DETAILED DESCRIPTION OF THE INVENTION

A first method of the present invention for manufacturing asemiconductor device is characterized in that, in a resin-sealing step,in a state where a thermal conductor is arranged with its concavityfacing up and the concavity of the thermal conductor is filled with aliquid resin, a plurality of semiconductor elements arranged on asubstrate are dipped in the liquid resin in the concavity and the liquidresin is solidified. According to this manufacturing method, since themetal thin wires of the semiconductor device will not be shorted duringthe manufacturing process, and furthermore, since a problem of imperfectfilling of resin will not occur, semiconductor devices with stablequality can be manufactured.

A second method of the present invention for manufacturing asemiconductor device is characterized in that, in a resin-sealing step,in a state where a thermal conductor is arranged with its concavityfacing up and the concavity of the thermal conductor is filled with aliquid resin, a plurality of semiconductor elements arranged on a leadframe are dipped in the liquid resin in the concavity and the liquidresin is solidified. According to this manufacturing method, since themetal thin wires of the semiconductor device will not be shorted duringthe manufacturing process, and furthermore, since a problem of imperfectfilling of resin will not occur, semiconductor devices with stablequality can be manufactured.

A first semiconductor device of the present invention includes asemiconductor element, a substrate on which the semiconductor element ismounted, a thermal conductor, and a sealing resin that is provided tothe spacing between the substrate and the thermal conductor so as toseal the semiconductor element. The thermal conductor is bonded to thesurface of the sealing resin so as to cover the sealing resin.

A second semiconductor device of the present invention includes asemiconductor element, a lead frame on which the semiconductor elementis mounted, a thermal conductor, and a sealing resin that is provided tothe spacing between the lead frame and the thermal conductor so as toseal the semiconductor element. The thermal conductor is bonded to thesurface of the sealing resin so as to cover the sealing resin.

Based on the above-described configurations, the semiconductor deviceand the method for manufacturing the semiconductor device of the presentinvention can be varied as described below.

Namely, in the first method for manufacturing a semiconductor device,the state where the concavity of the thermal conductor is filled with aliquid resin can be obtained by injecting the liquid resin into theconcavity of the thermal conductor.

Alternatively, the state where the concavity of the thermal conductor isfilled with a liquid resin can be obtained by casting a solid resin intothe concavity of the thermal conductor and by heating the thermalconductor so as to melt the solid resin.

The thermal conductor before the separation step can be provided as agroup of joined thermal conductors, and the separation step can becarried out by cutting the substrate and the thermal conductor groupsimultaneously.

The thermal conductor before the separation step can be provided as agroup of joined thermal conductors, and the separation step can becarried out by cutting the substrate, the thermal conductor group andthe sealing resin simultaneously.

In the second method for manufacturing a semiconductor device, the statewhere the concavity of the thermal conductor is filled with a liquidresin can be obtained by injecting the liquid resin into the concavityof the thermal conductor.

Alternatively, the state where the concavity of the thermal conductor isfilled with a liquid resin can be obtained by casting a solid resin intothe concavity of the thermal conductor and by heating the thermalconductor so as to melt the solid resin.

The thermal conductor before the separation step can be provided as agroup of joined thermal conductors, and the separation step can becarried out by cutting the lead frame and the thermal conductor groupsimultaneously.

The thermal conductor before the separation step can be provided as agroup of joined thermal conductors, and the separation step can becarried out by cutting the lead frame, the thermal conductor group andthe solidified resin simultaneously.

In the first and second methods of manufacturing a semiconductor device,the resin-sealing step can be carried out by sealing a plurality ofsemiconductor elements simultaneously.

The thermal conductor group can include the thermal conductors formed ina strip. Alternatively, the thermal conductor group can include thethermal conductors formed in a matrix. It is also possible that slitsare formed at the joints between the thermal conductors of the thermalconductor group.

In the first semiconductor device, the thermal conductor can beconfigured to cover the entire surface of the sealing resin.Alternatively, it is possible that the sealing resin is exposed from thesurface composed of the side face of the substrate and also the sideface of the thermal conductor.

It is also possible that the sealing resin is exposed from twoside-faces opposed to each other. Alternatively, the sealing resin canbe exposed from all of the side faces.

The electrode of the semiconductor element and the wirings of thesubstrate can be connected electrically to each other by the metal thinwires. Alternatively, the electrode of the semiconductor element and thewirings of the substrate can be connected electrically via bumps.

The surface of the semiconductor element opposite to the surface onwhich a circuit is formed can be configured to be in contact with thethermal conductor.

In the second semiconductor device, the thermal conductor can beconfigured to cover the entire surface of the sealing resin.Alternatively, the sealing resin can be exposed from the surfacecomposed of the side face of the lead frame and the side face of thethermal conductor.

It is also possible that the sealing resin is exposed from twoside-faces opposed to each other. Alternatively, the sealing resin canbe exposed from all of the side faces.

Alternatively, the thermal conductor can be adhered to the lead framethrough an insulating adhesive member.

Embodiment 1

A configuration of a semiconductor device according to Embodiment 1 ofthe present invention will be described below. FIG. 1 includes views forshowing the configuration of a semiconductor device 1 a in Embodiment 1of the present invention. FIG. 1A is a top view of the semiconductordevice 1 a, and FIG. 1B is a cross-sectional view taken along the lineA-A′ in FIG. 1A.

As shown in FIG. 1B, wiring patterns 12 are formed on both surfaces of asubstrate 13 made of an insulating resin. The wiring patterns 12 areconnected electrically to each other through viaholes 17. Asemiconductor element 11 a is adhered to the substrate 13 through anadhesive 14. An electrode is formed on the upper surface of thesemiconductor element 11 a and connected to the wiring pattern 12through metal thin wires 15. A sealing resin 16 seals integrally thesemiconductor-element-mounting surface of the substrate 13, thesemiconductor element 11 a, the adhesive 14 and the metal thin wires 15.

A thermal conductor 19 is made of a material having preferable thermalconductivity, such as Cu, Cu alloy, Al, Al alloy, and Fe—Ni alloy. Thethermal conductor 19 is shaped like a hat, and it has a contact portion19 a, an inclined portion 19 b formed with an inclination from thecontact portion 19 a, and a flat portion 19 c formed continuously fromthe inclined portion 19 b and in parallel to the contact portion 19 a.That is, the thermal conductor 19 has a concavity defined by theinclined portion 19 b and the flat portion 19 c. The contact portion 19a is in contact with the substrate 13, and the concavity is bonded tothe sealing resin 16 to cover the sealing resin 16. The thermalconductor 19 can be in contact with the substrate 13 and further adheredsecurely to the substrate 13 with an adhesive (not shown) or the like.The openings 131 as shown in FIG. 18 are not formed in the thermalconductor 19.

The flat portion 19 c of the thermal conductor 19 is exposed entirely orpartially from the sealing resin 16 to the exterior. Ball electrodes 18are arranged in a matrix on a surface (ball-formation surface) of thesubstrate 13 opposite to the semiconductor-element-mounting surface, andconnected electrically to the wiring pattern 12 of the substrate 13.

In the configuration of the semiconductor device 1 a, the heat generatedby the semiconductor element 11 a is diffused through the viaholes 17and the ball electrodes 18, and furthermore the heat is diffused alsofrom the semiconductor-element-mounting surface of the substrate 13through the thermal conductor 19. Therefore, the semiconductor device lahas excellent heat diffusion. Since the exterior of the thermalconductor is not provided with a sealing resin, the heat diffusionefficiency is improved further. Furthermore, by providing a heat sink orthe like (not shown) on the part at which the thermal conductor 19 isexposed from the sealing resin 16, the effect of heat diffusion of thesubstrate 13 from the semiconductor-element-mounting surface can beimproved further.

Unlike a conventional configuration, in the semiconductor deviceaccording to this embodiment, there is no necessity of forming openingsin the thermal conductor for the purpose of injecting a sealing resin,and thus the effect of suppressing electromagnetic noise received oremitted by the semiconductor device will be improved.

Next, a method for manufacturing the semiconductor device 1 a accordingto the present embodiment will be described below. FIGS. 2A-2F arecross-sectional views showing a process for manufacturing thesemiconductor device 1 a.

First, as shown in FIG. 2A, a substrate 13 having wiring patterns 12formed on both the surfaces is prepared, and an adhesive 14 is appliedon the predetermined positions of semiconductor-element-mounting surfaceof the substrate 13. Next, as shown in FIG. 2B, semiconductor elements11 a are arranged on the adhesive 14 applied on the predeterminedpositions of the substrate 13 and adhered securely. Next, as shown inFIG. 2C, electrodes (not shown) of the semiconductor elements 11 amounted on the substrate 13 are connected electrically to electrodes ofthe wiring patterns 12 formed on the semiconductor-element-mountingsurface of the substrate 13 through the metal thin wires 15. Theprocesses by this step are common to those in the method formanufacturing the conventional semiconductor device 101 as shown inFIGS. 19A-19C.

Next, a thermal conductor group 41 as shown in FIG. 2D is prepared byintegrally forming a plurality of thermal conductors 19. The thermalconductor group 41 is formed by etching or pressing a metal plate madeof a material having a preferable thermal conductivity, such as Cu, Cualloy, Al, Al alloy and Fe—Ni alloy so as to form concavitiesintegrally. The shape of the thermal conductor 19 is not limited to thequadrangle as shown in the present embodiment, but it may be round orpolygonal.

FIG. 3 is a top view showing the thermal conductor group 41 a formed byaligning and integrating a plurality of thermal conductors 19. Thethermal conductor group 41 a includes the thermal conductors 19 formedin a line in accordance with the pitch for mounting the semiconductorelements with respect to the substrate on which the semiconductorelements will be mounted. The cutoff line 43 indicates a line alongwhich the thermal conductor group 41 is cut and separated to form aplurality of thermal conductors 19.

FIG. 4 is a top view showing a thermal conductor group 41 b formed byintegrating a plurality of thermal conductors 19 arranged in a matrix.The thermal conductor group 41 b includes the thermal conductors 19formed in a matrix in accordance with the pitch for mounting thesemiconductor elements with respect to the substrate 13 on which thesemiconductor elements 11 a will be mounted. It is possible to seal aplurality of semiconductor elements 11 a simultaneously by using thethermal conductor group 41 a or 41 b.

FIG. 5 is an enlarged top view of a part of the thermal conductor group41 a. In the thermal conductor group 41 a, slits 44 are formed along thecutoff line 43 for easy cutting.

Next, as shown in FIG. 2D, the sealing resin 16 is injected into theconcavity of the thermal conductor group 41 in a state where the thermalconductor group 41 is set so that the surface facing the semiconductorelements 11 a is turned upward (i.e., the concavity is faced up). Atthis time, for the sealing resin 16, a liquid resin is injected.Alternatively, a solid resin is cast and heated to be melted in theconcavity of the thermal conductor group 41. Here, thesemiconductor-element-mounting surface of the substrate 13 is turneddownward, and the contact portion 19 a of the thermal conductor 19 isbrought into contact with the substrate 13 while dipping thesemiconductor element 11 a in a liquid sealing resin 16, and thus aresin-sealing is carried out.

In this process where the thermal conductor group 41 is employed inplace of the mold 134 used in the sealing step in the method formanufacturing a conventional semiconductor device as shown in FIG. 19D,the steps shown in FIG. 19D and 19E are combined into the step as shownin FIG. 2D, thereby decreasing the number of steps. Moreover, aresin-sealing can be carried out without using an expensive mold. Inaddition, unlike the resin-sealing step included in the side gatemethod, a resin will flow less. And thus problems such as deformation ofthe metal thin wires 15 can be suppressed.

Next, as shown in FIG. 2E, the ball electrodes 18 are formed in a matrixin accordance with the wiring pattern 12 formed on the ball-formationsurface of the substrate 13. Finally, as shown in FIG. 2F, thecomponents are separated by cutting with a rotary blade 42 for each ofthe semiconductor elements 11 a. In this manner, the semiconductordevice 1 a as shown in FIG. 1 can be manufactured. When the thermalconductor group 41 and the substrate 13 are cut with the rotary blade42, metal chips of the thermal conductor group 41 are generated.However, since the slits 44 are formed in the thermal conductor group 41along the cutoff line 43, the amount of the metal chips can bedecreased. As a result, adhesion of the metal chips to the semiconductordevice 1 a is reduced.

FIG. 6A is a top view showing a semiconductor device 1 b as a variationof the semiconductor device 1 a. FIG. 6B is a cross-sectional view takenalong the line B-B′ in FIG. 6A. The contact portion 20 a does not reachthe rim of the substrate 13, and it is not connected to a thermalconductor adjacent to the thermal conductor 20 in the manufacturingprocess. By using this thermal conductor 20, metal chips can be reducedat the time of separating the semiconductor devices, and thus adhesionof the metal chips to the semiconductor device can be reduced.

Embodiment 2

A semiconductor device according to Embodiment 2 of the presentinvention will be described below. FIG. 7A is a top view showing theconfiguration of a semiconductor device 2 a in the present embodiment.FIG. 7B is a cross-sectional view taken along the line C-C′ in FIG. 7A.FIG. 7C is a cross-sectional view taken along the line D-D′ that isperpendicular to the line C-C′ in FIG. 7A. In the following descriptionof embodiment, the same reference numerals may be assigned to the samecomponents as those of the semiconductor device 1 a in Embodiment 1 inorder to avoid the duplication of explanations.

The thermal conductor 21 shown in FIG. 7B is made of a material having apreferable thermal conductivity, such as Cu, Cu alloy, Al, Al alloy andFe—Ni alloy. The thermal conductor 21 includes a contact portion 21 a,an inclined portion 21 b formed with an inclination from the contactportion 21 a, and a flat portion 21 c formed continuously from theinclined portion 21 b and in parallel to the contact portion 21 a. Theinclined portion 21 b and the flat portion 21 c define a concavity. Thecontact portion 21 a is in contact with the substrate 13, and theconcavity is bonded to the surface of the sealing resin 16 so as tocover the sealing resin 16. The thermal conductor 21 covers not theentire surface of the sealing resin 16, but as shown in FIG. 7C, thesealing resin 16 is exposed along the cross section of the separatedsemiconductor device at the both ends of the line D-D′ of thesemiconductor device 2 a. The thermal conductor 21 can be in contactwith the substrate 13 and furthermore adhered securely to the substrate13 with an adhesive (not shown) or the like. The flat portion 21 c ofthe thermal conductor 21 is exposed to the outside entirely or partiallyfrom the sealing resin 16. In this configuration, since the sealingresin is not provided outside the thermal conductor 21, the heatdiffusion efficiency is improved.

Next, a method for manufacturing the semiconductor device 2 a in thepresent embodiment will be described. FIGS. 8A-8F are cross-sectionalviews showing the process of manufacturing the semiconductor device 2 a.First, as shown in FIG. 8A, a substrate 13 with wiring patterns 12formed on both the surfaces is prepared, and an adhesive 14 is appliedon the predetermined positions of the semiconductor-element-mountingsurface of the substrate 13. Next, as shown in FIG. 8B, thesemiconductor elements 11 a are arranged on the adhesive 14 applied onthe predetermined positions of the substrate 13, and adhered securely.Next, as shown in FIG. 8C, electrodes of the semiconductor elements 11 amounted on the substrate 13 are connected electrically to the wiringpattern 12 formed on the semiconductor-element-mounting surface of thesubstrate 13 through the metal thin wires 15. The process up to thisstep is common to the process in the method for manufacturing theconventional semiconductor device 101 as shown in FIGS. 19A-19C.

Next, a thermal conductor group 45 as shown in FIG. 8D is prepared byintegrally forming a plurality of thermal conductors 21. The thermalconductor group 45 is formed by etching or pressing a metal plate madeof a material having a preferable thermal conductivity, such as Cu, Cualloy, Al, Al alloy and Fe—Ni alloy so as to form a concavityintegrally. The concavity of the thermal conductor 21 is shaped to coverthe plural semiconductor elements 11 a.

Next, as shown in FIG. 8D, the sealing resin 16 is injected into theconcavity of the thermal conductor group 45 in a state where the thermalconductor group 45 is placed so that the surface facing thesemiconductor elements 11 a is turned upward. At this time, for thesealing resin 16, a liquid resin is injected. Alternatively, a solidresin is cast and heated to be melted in the concavity of the thermalconductor group 45. Here, the semiconductor-element-mounting surface ofthe substrate 13 is turned downward, and the substrate 13 and thecontact portion 21 a are brought into contact with each other whiledipping the semiconductor elements 11 a in the liquid resin 16, and thusa resin-sealing is carried out.

Since the thermal conductor group 45 is employed in place of the mold134 used in the sealing step in the method for manufacturing aconventional semiconductor device as shown in FIG. 19D, the steps shownin FIG. 19D and 19E are combined into the step as shown in FIG. 8D,thereby decreasing the number of steps. In addition, the resin-sealingstep can be carried out without using an expensive mold. Furthermore,unlike the case of resin-sealing in a side gate method, a resin willflow less, and thus problems such as deformation of the metal thin wires15 can be suppressed.

Next, as shown in FIG. 8E, the ball electrodes 18 are formed in a matrixin accordance with the wiring pattern 12 formed on the ball-formationsurface of the substrate 13. Finally, as shown in FIG. 8F, thecomponents are cut and separated with a rotary blade 42 for each of thesemiconductor elements 11 a, and thus the semiconductor device 2 a asshown in FIG. 7 can be manufactured.

The above-described separation step in the manufacturing method relatesto a case of using a substrate 13 on which the semiconductor elements 11a are arranged in a strip. In this case, as shown in FIG. 7, thesemiconductor device 2 a is configured so that the sealing resin isexposed from two of the side faces opposed to each other among the crosssections of the separated semiconductor devices 2 a.

FIG. 9A is a top view showing a semiconductor device 2 b as a variationof the semiconductor device 2 a. FIG. 9B is a cross-sectional view takenalong the line E-E′ in FIG. 9A. The thermal conductor 22 consists ofonly a flat portion, and the sealing resin 16 is exposed from all of theside faces. Even with this configuration, effects comparative to thoseof the semiconductor device 2 b can be obtained.

The process for manufacturing the semiconductor device 2 b issubstantially same as the process for manufacturing the semiconductordevice 2 a except for the use of a thermal conductor group formed suchthat the flat portion is shaped to cover semiconductor chips arranged ina matrix, in the step as shown in FIG. 8D.

Embodiment 3

A semiconductor device according to Embodiment 3 of the presentinvention will be described below. FIG. 10A is a top view showing aconfiguration of a semiconductor device 3 in Embodiment 3 of the presentinvention. FIG. 10B is a cross-sectional view taken along the line F-F′in FIG. 10A. In the following description of embodiment, the samereference numerals may be assigned to the same components as those ofthe semiconductor device 1 a in Embodiment 1 in order to avoid theduplication of explanations.

A semiconductor element 11 c has an electrode formed on the lowersurface (circuit-formation surface). Bumps 24 connect the electrode (notshown) on the semiconductor element 11 c and a wiring pattern 12 on thesemiconductor-element-mounting surface of the substrate 13. The spacingbetween the semiconductor element 11 c and the substrate 13 is filledwith a resin 25, except for the region where the bumps 24 are formed.

A thermal conductor 23 is made of a material having preferable thermalconductivity, such as Cu, Cu alloy, Al, Al alloy and Fe—Ni alloy. Thethermal conductor 23 includes a contact portion 23 a, an inclinedportion 23 b formed with an inclination from the contact portion 23 a,and a flat portion 23 c formed continuously from the inclined portion 23b and in parallel to the contact portion 23 a. The inclined portion 23 band the flat portion 23 c define a concavity. The contact portion 23 ais in contact with the substrate 13, and the concavity is bonded to thesurface of the sealing resin 16 so as to cover the sealing resin 16.

The flat portion 23 c is in contact with the upper surface of thesemiconductor element 11 c. The contact portion 23 a may be in contactwith the substrate 13 and further adhered securely to the substrate 13with an adhesive (not shown) or the like. The flat portion 23 c of thethermal conductor 23 is exposed entirely or partially to outside fromthe sealing resin 16.

As mentioned above, in the configuration where the flat portion 23 c ofthe thermal conductor 23 and the upper surface of the semiconductorelement 11 c are in contact with each other, the heat generated at thesemiconductor element 11 c is conducted efficiently to the thermalconductor 23, and thus the heat diffusion efficiency at thesemiconductor element 11 c is improved. Moreover, since the sealingresin is not provided outside the thermal conductor 23, the heatdiffusion efficiency is improved further. The heat diffusion efficiencyat the semiconductor element 11 c can be improved even further byproviding a heat sink or the like at the flat portion 23 c.

Unlike the conventional semiconductor device, the semiconductor deviceaccording to the present embodiment does not need holes formed in thethermal conductor in order to inject a sealing resin, and thus theeffect of suppressing electromagnetic noise that is received or emittedby the semiconductor device.

Next, a method for manufacturing the semiconductor device 3 in thepresent embodiment will be described with reference to the attacheddrawings. FIGS. 11A-11F are cross-sectional views showing the processfor manufacturing the semiconductor device 3. First, as shown in FIG.11A, the bumps 24 are formed on the electrodes of the semiconductorelement 11 c. Next, as shown in FIG. 11B, a substrate 13 having wiringpatterns 12 formed on both the surfaces is prepared, and thesemiconductor elements 11 c are arranged on the predetermined positionsof the semiconductor-element-mounting surface of the substrate 13 bypressing the bumps 24 on the wiring pattern 12 of the substrate 13.Next, as shown in FIG. 11C, a liquid resin 25 is injected into the spacebetween the semiconductor elements 11 c and the substrate 13 by usingthe capillary phenomenon.

Next, a thermal conductor group 46 consisting of a plurality of thermalconductors 23 integrally formed is prepared. The thermal conductor group46 is formed by etching or pressing a metal plate made of a materialhaving preferable thermal conductivity, such as Cu, Cu alloy, Al, Alalloy and Fe—Ni alloy in order to shape concavities integrally. Theshape of the thermal conductor 23 is not limited to the quadrangle asshown in the present embodiment, but it can be round or polygonal. Thethermal conductor group 46 is formed in accordance with thesemiconductor elements arranged on the substrate 13, and it can includethe thermal conductors 23 formed in a strip as shown in FIG. 3 or formedin a matrix as shown in FIG. 4.

Next, as shown in FIG. 11D, in a state where the thermal conductor group46 is set so that the surface facing the semiconductor elements 11 c isturned upward, the sealing resin 16 is injected into the concavities ofthe thermal conductor group 46. At this time, for the sealing resin 16,a liquid resin is injected. Alternatively, a solid resin is cast andheated to be melted in the concavities of the thermal conductor group46. Next, the surface of the substrate 13 on which the semiconductorelements 11 c are mounted is turned downward, and the substrate 13 isbrought into contact with the contact portion 23 a of the thermalconductor 23 while dipping the semiconductor elements 11 c in the liquidsealing resin 16, and thus a resin-sealing is carried out. In a case ofcasting a solid resin, the solid resin can be one block or more than oneblocks, or a powder.

In this step, the thermal conductor group 46 is employed in place of themold 134 used in the sealing step in the method for manufacturing aconventional semiconductor device as shown in FIG. 19D, thereby thesteps shown in FIGS. 19D and 19E are combined into the step as shown inFIG. 11D, and thus the number of steps is decreased. Moreover, aresin-sealing can be carried out without using an expensive mold.

Next, as shown in FIG. 11E, the ball electrodes 18 are formed in amatrix in accordance with the wiring pattern 12 on the ball-formationsurface of the substrate 13. Finally, as shown in FIG. 11F, thecomponents are cut and separated with a rotary blade 42 for each of thesemiconductor elements 11 a, and thus the semiconductor device 3 asshown in FIG. 10 is manufactured.

The semiconductor device 3 in the present embodiment has an internalstructure as a flip-chip package where the electrodes of thesemiconductor elements 11 c and the electrodes of the wiring patterns 12are connected to each other via bumps. However, the present invention isnot limited to this embodiment. The semiconductor device can beconfigured by using the thermal conductor 21 similar to that ofEmbodiment 2 so that the sealing resin is exposed from the end faces ofthe package.

Embodiment 4

A semiconductor device according to Embodiment 4 of the presentinvention will be described below. FIG. 12A is a top view showing aconfiguration of a semiconductor device 4 a in Embodiment 4 of thepresent invention. FIG. 12B is a cross-sectional view taken along theline G-G′ in FIG. 12A. In the following description of embodiment, thesame reference numerals may be assigned to the same components as thoseof the semiconductor device 1 a in Embodiment 1 in order to avoid theduplication of explanations.

A lead frame 27 for inputting/outputting from/to the exterior includes adie pad portion 28 and a lead portion 29. On the die pad portion 28, asemiconductor element 11 a is arranged through an adhesive 14. The leadportion 29 is connected to an electrode on the upper surface of thesemiconductor element 11 a through a metal thin wire 15.

The thermal conductor 26 is made of a material having a preferablethermal conductivity, such as Cu, Cu alloy, Al, Al alloy and Fe—Nialloy, and arranged to cover the sealing resin 16. The thermal conductor26 includes a flat portion 26 c and an inclined portion 26 b formed withan inclination from the flat portion 26 c. The inclined portion 26 b andthe flat portion 26 c define a concavity. The concavity of the thermalconductor 26 is adhered to the surface of the sealing resin 16 so as tocover the sealing resin 16. The thermal conductor 26 is adhered to thelead frame 27 through the sealing resin 16. The flat portion 26 c of thethermal conductor 26 is exposed entirely or partially to the exteriorfrom the sealing resin 16. In this configuration, since the sealingresin is not provided outside the thermal conductor 26, the heatdiffusion efficiency is improved.

Unlike the conventional semiconductor device, the semiconductor deviceaccording to the present embodiment does not need holes formed in thethermal conductor in order to inject a sealing resin, and thus theeffect of suppressing electromagnetic noise that is received or emittedby the semiconductor device will be improved.

Next, a method for manufacturing the semiconductor device 4 a in thepresent embodiment will be described below. FIGS. 13A-13F arecross-sectional views showing the process for manufacturing thesemiconductor device 4 a.

First, as shown in FIG. 13A, a tape 30 is stuck to a lead frame 27including a die pad portion 28 on which semiconductor elements aremounted and a lead portion 29, on the surface opposite to thesemiconductor-element-mounting surface. Next, an adhesive 14 is appliedon the semiconductor-element-mounting surface of the die pad portion 28.Next, as shown in FIG. 13B, the semiconductor element 11 a is arrangedand adhered securely on the adhesive 14 applied on the die pad portion28. Next, as shown in FIG. 13C, electrodes on the upper surface of thesemiconductor element 11 a mounted on the adhesive 14 and the leadportion 29 are connected electrically to each other through the metalthin wires 15.

Next, a thermal conductor group 47 as shown in FIG. 13D is prepared byintegrating a plurality of thermal conductors 26. The thermal conductorgroup 47 is formed by etching or pressing a metal plate made of amaterial having preferable thermal conductivity, such as Cu, Cu alloy,Al, Al alloy and Fe—Ni alloy in order to shape a plurality ofconcavities for covering a plurality of semiconductor elements 11 a. Forfacilitating a subsequent step of cutting to each semiconductor element,the inclined portions 26 b of the semiconductor devices to be separatedare joined to form a groove in the cut region. This groove is helpful inreducing the cutting area in separating the components, thereby reducingthe load applied to the semiconductor devices and to the rotary blade,and also reducing the amount of the cutting chips.

Next, as shown in FIG. 13D, the sealing resin 16 is injected into theconcavities of the thermal conductor group 47 in the state where thethermal conductor group 47 is set so that the surface facing thesemiconductor elements 11 a is turned upward. At this time, for thesealing resin 16, a liquid resin is injected. Alternatively, a solidresin is cast and heated to be melted in the concavities of the thermalconductor group 47. In a state where the surface of the lead frame 27 onwhich the semiconductor elements 11 a are mounted is turned downward,the lead portion 29 is brought into contact with the thermal conductorgroup 47 while dipping the semiconductor elements 11 a in the liquidsealing resin 16, and thus a resin-sealing is carried out. In a case ofcasting a solid resin, the solid resin can be one block or more than oneblocks, or a powder.

In this process where the thermal conductor group 47 is employed inplace of the mold 134 used in the sealing step in the method formanufacturing a conventional semiconductor device as shown in FIG. 19D,the steps shown in FIG. 19D and 19E are combined into the step as shownin FIG. 13D, thereby decreasing the number of steps. In addition, theresin-sealing can be carried out without using an expensive mold.Furthermore, unlike the case of resin-sealing in a side gate method, theresin will flow less, and thus problems such as deformation of the metalthin wires 15 can be suppressed.

Next, as shown in FIG. 13E, the tape 30 is removed from the lead frame27. Finally, as shown in FIG. 13F, the inclined portion 26 b and thelead portion 29 are cut off with the rotary blade 42. In this manner,the semiconductor device 4 a is manufactured.

Though the inclined portions 26 b are provided to form grooves in thethermal conductor group 47 in this embodiment, the grooves are notformed necessarily. FIG. 14A is a top view showing a configuration of asemiconductor device 4 b as a variation of the semiconductor device 4 a.FIG. 14B is a cross-sectional view taken along the line H-H′ in FIG.14A. The thermal conductor 31 does not have an inclined portion. Thissemiconductor device 4 b is obtained without forming a groove betweenthe respective thermal conductors 31 of the thermal conductor group 47.

Unlike the semiconductor device in FIG. 12B, the semiconductor device asshown in FIG. 14B has a thermal conductor configured without anyinclined portions 26 b. This semiconductor device is as advantageous asthe semiconductor device 4 a shown in FIG. 12B in that there is nonecessity of using an expensive mold and that the metal thin wires 15are resistant to deformation.

When taking the heat diffusion into consideration, it is preferable thatthe thermal conductor 26 shown in FIG. 12B is positioned in the vicinityof the lead portion 29. FIG. 15A is a top view showing a configurationof a semiconductor device 4c as a variation of the semiconductor device4 a. FIG. 15B is a cross-sectional view taken along the line I-I′ inFIG. 15A. The thermal conductor 32 has an inclined portion 32 b thatextends to form a peripheral flat portion 32 d. The peripheral flatportion 32 d is adhered to the lead portion 29 through an insulatingadhesive member 33. As a result, the heat escapes from the lead portion29 to the thermal conductor 32, and thus the heat diffusion is improvedfurther in comparison with the semiconductor device 4 a.

The method for manufacturing the semiconductor device 4 c will bedescribed below. Explanation of the steps common to those formanufacturing the semiconductor device 4 a will be omitted for avoidingthe duplication of explanations. After connecting the semiconductorelement 11 a and the lead portion 29 as shown in FIG. 13C through themetal thin wire 15, a thermal conductor group 47 b is prepared as shownin FIG. 16. The thermal conductor group 47 b has a plurality ofconcavities, and the grooves between the concavities are flattened toform peripheral flat portions 32 d.

Next, the sealing resin 16 is injected into the concavities of thethermal conductor group 47 b in a state where the thermal conductorgroup 47 b is positioned so that the surface facing the semiconductorelements 11 a is turned upward. Next, in a state where the lead frame 27is set with its surface on which the semiconductor elements 11 a aremounted is turned downward, the lead portion 29 and the thermalconductor group 47 b are adhered to each other through the adhesivemember 33 while dipping the semiconductor elements 11 a in a liquidsealing resin 16, and thus a resin-sealing is carried out. Next, thetape 30 is removed, and the thermal conductor group 47 b is cut off withthe rotary blade at the flat parts of the grooves. In this manner, thesemiconductor device 4 c is manufactured.

The semiconductor device 4 c configured as shown in FIG. 15B is asadvantageous as the semiconductor device 4 a in that there is nonecessity of using an expensive mold, and that the metal thin wires 15are resistant to deformation.

As mentioned above, since the thermal conductors are used as the sealingmolds for the semiconductor devices 1 a-4 c in Embodiments 1-4, the stepof mounting the thermal conductor and the resin-sealing step can becarried out simultaneously, thereby reducing the number of steps.Moreover, the resin-sealing can be carried out without using anexpensive sealing mold. As a result, there is no necessity of designing,manufacturing and maintaining the sealing mold, and thus the cost can bereduced remarkably. Furthermore, the size and the shape of the sealportion can be varied only by processing the thermal conductor, and thusthe shape can be varied with further flexibility.

In addition, since the resin-sealing is carried out by dipping thesemiconductor elements 11 a and 11 c in a liquid resin, deformation inthe metal thin wires can be suppressed, resulting in improvement inquality.

Therefore, the present invention can provide a highly qualifiedsemiconductor device. In other words, the semiconductor device can beshaped with less limitation, manufactured at a low cost, and it hasexcellent heat diffusion. The flat portions 19 c, 21 c, 23 c, 26 c, and32 c are not necessarily flat, but can be hemispherical. However,preferably the flat portion 23 is flat since this portion is required tobe in contact with the semiconductor element 11 c. Similarly, it ispreferable that the flat portions 19 c, 21 c, 23 c, 26 c, and 32 c areflat when a heat sink or the like is provided on such a flat portion.

The invention may be embodied in other forms without departing from thespirit or essential characteristics thereof. The embodiments disclosedin this application are to be considered in all respects as illustrativeand not limiting. The scope of the invention is indicated by theappended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are intended to be embraced therein.

1.-24. (canceled)
 25. A semiconductor device comprising: a semiconductorelement; a substrate on which the semiconductor element is mounted; athermal conductor; and a sealing resin provided to spacing between thesubstrate and the thermal conductor so as to seal the semiconductorelement, the thermal conductor is bonded to the surface of the sealingresin so as to cover the sealing resin.
 26. The semiconductor deviceaccording to claim 25, wherein the thermal conductor covers the entiresurface of the sealing resin.
 27. The semiconductor device according toclaim 25, wherein the sealing resin is exposed from a surface composedof the side face of the substrate and the side face of the thermalconductor.
 28. The semiconductor device according to claim 27, whereinthe sealing resin is exposed from two side-faces opposed to each other.29. The semiconductor device according to claim 27, wherein the sealingresin is exposed from all of the side faces.
 30. The semiconductordevice according to claim 25, wherein an electrode of the semiconductorelement and wirings of the substrate are connected electrically to eachother through metal thin wires.
 31. The semiconductor device accordingto claim 25, wherein an electrode of the semiconductor element andwirings of the substrate are connected electrically to each other viabumps.
 32. The semiconductor device according to claim 31, wherein asurface of the semiconductor element opposite to the surface on which acircuit is formed is in contact with the thermal conductor.
 33. Asemiconductor device comprising: a semiconductor element; a lead frameon which the semiconductor element is mounted; a thermal conductor; anda sealing resin provided to spacing between the lead frame and thethermal conductor so as to seal the semiconductor element, the thermalconductor is bonded to the surface of the sealing resin so as to coverthe sealing resin.
 34. The semiconductor device according to claim 33,wherein the thermal conductor covers the entire surface of the sealingresin.
 35. The semiconductor device according to claim 33, wherein thesealing resin is exposed from a surface composed of the side face of thelead frame and the side face of the thermal conductor.
 36. Thesemiconductor device according to claim 35, wherein the sealing resin isexposed from two side-faces opposed to each other.
 37. The semiconductordevice according to claim 35, wherein the sealing resin is exposed fromall of the side faces.
 38. The semiconductor device according to claim33, wherein the thermal conductor is adhered to the lead frame throughan insulating adhesive member.